Railway-track-circuit regulation



1921 2 Sheets-Sheet 1 C.- H. ZIEIRDT M 9 H v r0 RAILWAY TRACK CTRCUITREGULATION original F'ild Sept 30,

Jan. 4 1927.

. INVENTOR. & F? I (Q Z M 1 ATTORNEY Jan. 4, 1927. ,613,259

, A c. H. ZIERDT;

RAILWAY TRACK CTRCUIT REGULATION Filed se ix so. 1921 2 Sheets-Sheet 2 5i WY E94.

D 21 I23: I

INVENTOR'. CAN.

A'l 'ToRNEY Patented Jan. 4, 1927.

UNITED STATES PATENT;

CONRAD H. ZIERDT, OF PENN 'IOVVNSHIIP, ALLEGHENY COUNTY, PENNSYLVANIA,AS- SIGNOR TO THE UNION SWITCH 86 SIGNAL COMPANY, OF SWISSVALE, PENNSYL-VANIA, A CORPORATION OF PENNSYLVANIA.

RAILWAY-TRAOK-CIRCUIT REGULATION.

My invention relates to track circuits for railways, and has for anobject the provision of means for stabilizing the voltage across therails in such circuits.

The present application is a continuation of my co-pending applicationfiled Sept. 30, 1921, Serial No. 504321, for railway track circuitregulation, in so far as the sub ect matter common to the two isconcerned.

I will describe several forms of apparatus embodying my invention andwill then point out the novel features thereof in claims.

In the accompanying drawings, Fig. 1 1s a'diagrammatic view showing oneform of apparatus embodying my invention, and Figs. 2, 3, 4t, 5, 6, 7and 8 are views showing modifications of the apparatus shown in Fig. 1and also embodyingmy invention.

Similar reference characters refer to similar parts in each of theseveral views.

Referring first to Fig. 1, the reference character A designates asection of railway track which is electrically separated from theadjoining portions of track by insulated joints 12. The section A isprovided with a track circuit comprising the track rails 2 and 2, atransformer secondary 3 connected across the rails at one end of thesection, and a relay R having a winding l connected across the rails atthe other end of the section. The primary 5 of transformer T is, ofcourse, connected with a suitable source of alternating signalingcurrent which is not shown in the drawing.

In a combination such as that just described, it is desirable that thevoltage across the terminals of the relay winding 1 should be as nearlyconstant as possible, but in actual practice this voltage varies for anumber of reasons, one of which is that the electrical resistance of theballast between the rails 2 and 2 is lower in wet weather than in dryweather, so that the voltage across the relay winding is lower in wetthan in dry weather, assuming the voltage at the transformer end of thesection to be constant.

In order to stabilize the voltage at the relay R,I provide the trackcircuit with a reg ulator B comprising a heating element 6 connectedacross the rails 2 and 2 and a therino sensitive element 7 alsoconnected across This application filed December the rails and exposedto variations in the temperature of the heating element 6. Element 7 isalso in electrical contact with element 6. The thermo-sensitive element7 has the characteristic of decreasing in electrical resistance withincrease of temperature, that is, it has a negative temperaturecoefficient. As here shown, the regulator is located at about the middleof the track circuits, but I. do not desire to be limited to thisspecific location.

.The parts of the track circuit, including the regulator 3,1 are soadjusted that in wet weather the voltage at relay winding 4 is thedesired or normal value. Then as the ballast dries out, the ballastresistance increases so that the voltage across the heating element 6increases, with the result that the amount of current flowing in thiselement increases and the temperature of this element rises. This causesthe resistance of the thermo-sensitive element to decrease, so that morecurrent flows from rail ,to rail through this element, thereby loweringthe voltage across the rails. It follows that the voltage applied torelay R is more nearly constant than it would be without the regulator.

Referring now to Fig. 2, the regulator, which is here designated C,comprises a compression rheostat 8 in the form of a pile of carbon discsconnected across the track rails 2 and 2", a magnet 9 also connectedacross the rails, and an armature 1O controlled by by a rod 11. Theelectrical resistance of the rheostat decreases with increase. in thepressure exertedthereon iby armature 10, and, of course, this pressureincreases with increase of current in the magnet winding, that is, withincrease of voltage across the rails. It follows thatas the rail voltageincreases, the resistance of the rheostat decreases, and so theregulator tends to stabilize the voltage applied to relay winding 4. Aswith the apparatus shown in Fig. 1, the parts are so ad justed thatnormal voltage is applied to relay winding 4 when the rail ballast iswet.

In Fig. 8, the regulatorC is the same as in Fig. 2, but the rheostat andmagnet winding are connected in series across the track rails instead ofin multiple as shown in Fig. 2.

the magnet and connected with the rheostat The operation is the same asthat of the apparatus shown in Fig. 2.

Referring to Fig. 4-, the regulator, here designated by the referencecharacter B, comprises a cylindrical conductor 13. Covering thisconductor and attached thereto is a coating of thermo-sensitive material7. The heating element 6 comprises a coil of wire wound around theoutside of this therino-sensitive element and in contact therewith. Therail 2 is connected to one end of the heating element 6 and to theconductor 13 while the other end of the heating element 6 is connectedto the rail The operation of this regulator is precisely the same asthat of the regulator shown in Fig. 1.

In Fig. the regulator B" comprises two conductors let and 15 of someconducting material such as nickel, plated with copper, which arehelically wound or intertwined into a hollow tube in such a manner thatthe turns of one conductor alternate with the turns of the other. Eachconductor is covered with a coating of thermo-sensitive material such ascopper oxide, which is thus interposed between one conductor and theother. This coating may be conveniently applied by heating thecopper-plated conductors after they have been Wound together. Spaced inthe tube formed by these conductors is a heating element 16 having itsterminals connected to the conductors 1-61 and 15, respectively. Therail 2 is connected to one conductor 15 and rail 2 is connected to theother conductor 14. Now if the track voltage rises, the amount ofcurrent flowing in the heating element 16 increases thus rais ing thetemperature of this element. The heat so generated causes thetemperature of the thermo-sensitive material on conductors 14.- and 15to increase, so that more current is allowed to pass from one conductorto the other, that is. from rail to rail through the thern'io-sensitivematerial, thereby tending tolower the voltage across the rails. Theresult is a decrease in the voltage fluctuation at the relay R. i

The resistance of thermo-sensitive cells is normally very high except athigh temperatures, and so in some cases it is desirable to operate thesecells at higher voltages than are available in track circuits. As shownin Fig. 6, I accomplish this by means of a step up transformer T. Theprimary winding 17 of this transformer is connected across the rails ofsection A. and the terminals of the secondary winding 18 are connectedto two electrodes 21 of a thermo-sensitive cell D. Between these twoelectrodes is a high resistance element of thermo-sensitive materialsuch as a compressed mixture of pulverized copper oxide and silicate ofsodium. hen the voltage on the track increases, the voltage applied tothe thermo-sensitive element 20 also increases. This causes an increasedcurrent to flow through the element 2 1 which results in a decrease inits resist ance and a still greater increase in the current passingthrough this element. This results in a greater current from rail torail through winding 17 and the voltage is consequently more nearlyconstant at relay R than it would be without the regulator.

The main advantage of the apparatus shown in Fig. 6 is that since thethermosensitive cell is operated at higher voltages than thoseordinarily available in track circults, this cell can be made morerugged mechanically than a cell which must ope "ate on ordinary trackcircuit voltages. Furthermore, owing to the comparatively high voltageapplied to the cell the heater coil is probably not necessary, but iffound desirable the thermo-sensitive action of the cell may beincreased, as shown in F '7, by means of a heater coil 19 connectedacross the rails and so disposed that the heat generated in it serves toraise the temperature oi the thermosensitive element 20. The structureand operation of the regulator are otherwise the same as o t'thatshownin Fig. 6.

In Fig. 8 the regulator 13 of Fig. 5 is substituted for the regulator Dof Fig. 6. Its action is exactly as before but the operating range isincreased by the higher voltage supplied by the transformer T.

Apparatus embodying my invention as shown in Figs. 1-5 inclusive may beapplied to either direct current or alternating current track circuits,but when applied to an alternating current circuit it should be notedthat the regulator B or C does notdisturb the phase relations of thesystem because the current flowing in the thermo-sensitive element 7 ofFig. l and in the compression rheo-statelement 8 of Figs. 2 and 3 ispractically in phase with the leakage current in the rail ballast.Furthermore. inasmuch as these regulators stabilize the leakage currentbetween the rails, they also stabilize the phase of the currentdelivered to the track relay, that is, theytend to eliminate the variations in phase due to variations in conductivity of the trackballast.

Although I have herein shown and described only a few forms of apparatusembodying my invention, it is understood that various changes andmodifications may be made therein within the scope of the appendedclaims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination, a track circuit comprising the track rails of arailway and a track relay connected across said rails, a heating elementconnected across said rails in multiple with said relay, and athermosensitive element also connected across said rails in multiplewith said relay and exposed to variations in the temperature of saidheating element.

2. In combination, a track circuit comprising the track rails of arailway and a track relay connected across said rails, and athermo-sensitive relay comprising a heating element and athermo-sensitive element both of which are connected across said railsin multiple with said relay.

3. In combination, a track circuit comprising the track rails of arailway and a track relay connected across said rails, and

a thern'io-sensitive relay comprising a heatin;' element and athermo-sensitive element both of which are connected across said railsin multiple with said relay, said then mo-sensitive element havingthecharacteristic ot decreasing in electrical resistance as its temperatureincreases.

i. In combination, a track circuit conr rising the track rails of arailway and a track relay connected across said rails, athern'io-sensitive element connected across said ri ils in multiple withsaid relay, and a heating element also connected across said rails ini'nult-iple with said relay for varying the temperature of saidtliermo-sensitive element in response to variations in the voltageacross said rails.

5. In combination, a track circuit comprising the track rails of arailway and a relay, a conductor connected across said rails, and meansresponsive to variations in the current carried by said conductor forstabilizing the voltage across said rails.

6. In combination, a track circuit cornprising the track rails of arailway and a relay, a conductor connected across said rails in multiplewith said relay, and a device connected across said rails in multiplewith said relay and having the characteristic of varying in electricalresistance in response to variations in the current carried by saidconductor.

7. In combination, a section of railway track, a track circuit for saidsection co1nprising a source of current and a relay both connectedacross the rails of the section, a thermo-sensitive substance, twoconductors in contact with said substance and connected with the tworails respectively of said section, and an element connected across saidrails for heating said substance.

8. In combination, a section of railway track, a track circuit for saidsection comprising a source of current and a relay both connected acrossthe rails of the section, two helical conductors connected with the tworails respectively of said section and so disposed that the turns of onealternate with the turns of the other, a coating of thermosensitivesul'istance on each conductor, and an element connected across saidrails for heating said substance.

9; In combination, a track circuitconr prising the rails oi a railway, aconductor connected acros said rails, an electrode connected to one ofsaid rails, a second electrode connected to the other of said rails, andan element of thermo-sensitive material interposed between saidelectrodes and responsive to variations in the current carried by saidonductor.

10. In combination, a track circuit comprising the rails of a railway, aconductor connected across said rails, an electrode connected to one ofsaid rails, a second electrode com'iccted to the other said rails, andan element of tl'iermo-sensitive material interposed between saidelectrodes and responsive to variations in the temperature of the saidconductor.

In testimony whereof I ailix my signature.

CONRAD H. ZIERDT.

